Budesonide reduces sensitivity and reactivity to inhaled mannitol in asthmatic subjects

Objective: The aim of the study was to investigate whether treatment using inhaled corticosteroids decreases airway responsiveness to inhaled mannitol in asthmatic subjects. Methodology: Before treatment or a change in treatment with inhaled corticosteroids, 18 asthmatic subjects had measurements of lung function and air-way sensitivity to mannitol taken and they completed a self-administered questionnaire on asthma symptoms. The procedure was repeated 6-9 weeks after taking 800-2400 mug/day of budesonide. dResults: There were significant reductions in airway sensitivity (provoking dose to induce a 15% fall in FEV1 (PD15)) and airway reactivity measured by the response dose ratio (RDR; final percentage fall FEV1/total dose of mannitol administered). The PD15 (Gmean (95%Cl)) increased from 78 mg (51, 117) before treatment to 289 mg (202,414) following treatment (P< 0.001). All subjects had a significant increase beyond the repeatability of 0.9 doubling doses with seven subjects becoming unresponsive. There was a 4.2 (3.4, 4.9)-fold improvement in the RDR with the value before the treatment period 0.18 (0.12, 0.28) decreasing to 0.04 (0.03, 0.08) following treatment (P< 0.001). These improvements were associated with significant improvements in lung function and symptom severity. Conclusion: Treatment with the inhaled corticosteroid budesonide caused a decrease in airway sensitivity and reactivity to inhaled mannitol and this was associated with expected improvements in lung function and symptoms.